Beavers reintroduced to degraded watersheds in Washington state have restored wetland ecosystems, reduced wildfire damage, and improved salmon habitat, according to years of monitoring by state agencies and university researchers.
In the early 2000s, the Methow and Yakima watersheds had been severely damaged by drought and wildfires that consumed 70 percent of the region’s forests. The ground could not absorb rainfall, mudslides followed storms, and fish populations collapsed. Engineers built concrete reservoirs and artificial ponds at costs ranging from $500,000 to $2 million each, but most of these projects failed. A 2017 University of Idaho study found that human-built structures could not replicate the work of live beavers.
Beavers had once been abundant across North America, with estimates ranging from 60 million to 400 million animals before the fur trade nearly eliminated them by the early 1900s. When the beavers disappeared, their dams crumbled, and the ecosystems that depended on them degraded.
In 2007, wildlife biologists began relocating beavers that had become nuisances in cities, transporting them to the degraded watersheds instead of killing them. The animals built dams from whatever materials were available, including grass, sagebrush, and small rocks. When spring snowmelt arrived, water spread across the parched soil instead of rushing downstream. Within months, soil moisture increased by 30 to 40 percent, and springs that had been dry for years began flowing again.
Vegetation returned as willows, cottonwoods, and aspens took root along the new ponds. Birds and insects followed. Within three years, valleys that had been barren supported lush green corridors. Salmon returned to streams where water temperatures had dropped below the threshold needed for their eggs to survive. Fish densities in beaver-influenced areas were four to five times higher than in streams without beavers.
During five major wildfires over a decade, only 2 to 3 percent of trees burned in areas where beavers had built wetlands, compared with up to 60 percent in areas without them. Relocating a beaver pair costs $2,000 to $3,000, while fighting large wildfires costs tens of millions of dollars. Farmers in the region reported that their wells no longer ran dry and that groundwater aquifers were recharging.
By 2021, more than 240 beavers had been released across 50 sites in the Methow watershed, with 64 percent establishing territories. The project expanded to other regions. In 2011, a beaver dam in Canada trapped oil from a pipeline leak, preventing contamination of a downstream river. In the Chesapeake Bay region, beaver ponds removed 45 percent of nitrogen pollution that would have cost wastewater treatment plants millions to address.
In May 2025, ecologists in the Czech Republic reported that eight beavers released near the Bodin wetland built a chain of functioning dams within two days, after officials had spent seven years and over 30 billion trying to restore the site through conventional engineering. Crayfish, frogs, and migratory birds returned within weeks.
The Washington project continues to expand, with plans to restore at least 500 kilometers of streams using beaver engineering over the next decade. A 2024 report from the Washington State Department of Ecology found that areas with beavers held 15 to 20 percent more water during summer months, and wildfire risk had dropped by 40 percent. Researchers now use thermal sensors, soil moisture monitors, drones, and GPS collars to track the effects. Indigenous communities have joined the effort, sharing traditional knowledge about the landscape.
The parachute beaver project in Idaho, conducted in 1948, demonstrated the long-term effects of beaver reintroduction. Idaho Fish and Game officials used surplus World War II parachutes to drop 76 beavers into the remote Chamberlain Basin, an area too rugged for trucks or mules. Seventy-five of the animals survived the drop and established colonies. Satellite images taken decades apart show the valley transformed from barren ground to a green corridor with ponds and wetlands. Plant diversity in the area rose by nearly one-third, and the landscape held water longer during dry periods.
The largest known beaver dam, located in Canada’s Wood Buffalo National Park, spans 850 meters and is visible from space. It was built by multiple generations of beavers over several decades.
In Utah, the Price River had been degraded by the Milford Flat fire in 2007, which burned 567 square miles. The fire destroyed vegetation along the riverbanks, and subsequent storms sent sediment into the river. Water temperatures exceeded 100 degrees Fahrenheit in some stretches, making the river uninhabitable for native fish. Conventional restoration projects cost between $500,000 and $2 million each and required constant maintenance.
In 2019, researchers from Utah State University began relocating beavers from areas where they were considered nuisances. Forty-seven beavers were moved to the Price and San Rafael rivers at a cost of $2,000 to $3,000 per pair. Some animals died from predation shortly after release, and others wandered long distances. But the beavers that established territories built dams that slowed the river’s flow from 3 feet per second to 1.6 feet per second. Groundwater levels rose 3 to 5 feet near active dams, and fish, insects, and amphibians returned to the water.
By 2025, the Salt Lake Tribune reported that the Price River’s recovery had helped revitalize the town of Helper, where residents now kayak and fish in water that had been reduced to mud a decade earlier. The project has become a model for low-cost river restoration in arid regions.
New York Harbor, once home to oyster reefs covering 220,000 acres, lost its oyster population by the 1920s due to overharvesting and industrial pollution. The reefs had filtered the water, provided habitat for marine life, and protected the shoreline from storms. In 1927, health officials closed the last commercial oyster grounds after the water became unsafe.
The Clean Water Act of 1972 changed the trajectory of the harbor by requiring the city to treat its sewage. In the early 2000s, scientists found wild oysters clinging to old pilings, a sign that the water had improved enough to support marine life again.
In 2014, educators Pete Malinowski and Murray Fisher launched the Billion Oyster Project, based at the New York Harbor School on Governors Island. The project collected discarded oyster shells from more than 75 restaurants across the city. Students and volunteers cleaned and cured the shells for a year, then seeded them with oyster larvae bred in tanks on the island. The seeded shells were placed in cages and reef balls in the harbor.
By 2025, more than 130 million live oysters had been established across nearly 19 acres of reef. Surveys documented 32 to 37 species living on the reef structures. At one site, 5.8 million wild oysters settled naturally without human intervention, indicating that water quality had crossed a threshold that allowed natural reproduction.
The project has faced setbacks. Disease, combined sewer overflows, and heat waves have caused die-offs in some reefs. Engineers have adapted by using modular cages and placing oysters deeper in the water where temperatures are more stable. The oysters remain off-limits for harvesting, and regulators require monitoring and tagging at every site.
The project has also supported shoreline protection efforts. After Hurricane Sandy in 2012, planners in Staten Island received a $60 million grant from the Department of Housing and Urban Development to build living breakwaters made of oyster-encrusted structures. Computer models suggest these breakwaters can reduce wave energy by up to 80 percent during storms at roughly one-third the cost of traditional seawalls.
More than 10,000 students have participated in the project through the Harbor School and partner programs, and several have gone on to careers in marine science. The project has drawn interest from officials in Tokyo, London, and Cape Town.
A parasitic flatworm, Raillietiella orientalis, has spread through Florida’s snake populations since arriving with imported Burmese pythons. The parasite, a pentastome related to crustaceans, lives in the lungs of snakes and feeds on their blood. Infected snakes often die from the damage, with heavy infestations making normal breathing impossible.
The parasite originated in Southeast Asia, where it coexists with Burmese pythons. When pythons entered Florida through the exotic pet trade in the 1990s, the parasites traveled with them. The parasite has since jumped to native snake species. It spreads through a multi-stage life cycle involving cockroaches and lizards, which carry the larvae between hosts.
By 2023, infections had been confirmed in more than 34 counties across Florida, including the panhandle. At least 18 native snake species have been identified as hosts, including the federally threatened eastern indigo snake. The parasite has been found in Alabama, and Georgia is monitoring for its arrival. Roadkill surveys conducted by the Snake Lungworm Alliance and Monitoring network, known as SLAM, have been the main tool for tracking the spread.
In the mid-20th century, farmers in Washington state’s Walla Walla Valley struggled to produce alfalfa seed because honeybees, the standard commercial pollinator, learned to bypass the alfalfa flower’s pollination mechanism. The flower requires a pollinator to press down on its keel to release pollen, and honeybees avoided this by piercing the flower from the side to access nectar.
Researchers at Washington State University identified the alkali bee as an effective pollinator for alfalfa. These native ground-nesting bees, found in salty barren patches of soil, triggered the flower’s mechanism consistently. Researchers and growers developed methods to create alkali bee habitat by spreading rock salt on soil, installing subsurface irrigation systems with gravel and perforated pipes, and maintaining a specific balance of moisture and salt.
Some families dedicated dozens of acres to bee beds, land that could have grown other crops. County officials reduced speed limits on roads bordering the beds to reduce dust and vibration that could disrupt the bees. By the 1960s, the Walla Walla Valley was producing about a quarter of all alfalfa seed grown in the United States, with annual regional revenue reaching $42 million. One acre of bee bed can service more than 100 acres of alfalfa, producing up to 100,000 pounds of seed.
The system remains vulnerable to flooding and pesticide use. Growers have installed drainage systems and remote sensors, and they follow strict pest management protocols that limit spraying to times when bees are underground. Extension scientists from Washington State University continue to provide technical support.
The Kubuqi Desert in Inner Mongolia, covering more than 7,000 square miles, expanded for decades until the 1980s, burying villages and farmland. Earlier government programs, including windbreak forests and grazing bans, had limited success. In 1988, Wang Wenbao, a former teacher who had become head of a local salt works, began a tree-planting program funded by setting aside five yuan for every ton of salt sold. The program grew, and Wang and local farmers planted hundreds of millions of drought-resistant willows.
The willows anchored the sand, but the soil still lacked organic matter. Wang introduced Rex rabbits, which were raised in closed systems and fed on dry grass and willow shoots. Rabbit manure, rich in nitrogen and phosphorus, was mixed into the sand with fallen leaves. The system produced more than 5 tons of organic matter per acre annually, improving the soil’s ability to hold water and support crops.
By 2021, satellite images showed green vegetation covering about 1,200 square miles of previously barren land. Wind speeds had dropped, and more than 15 million tons of sand were held in place annually. Groundwater levels rose in some areas. The Junma solar farm, built on stabilized land with nearly 200,000 panels, generates hundreds of millions of kilowatt hours annually, with sheep and rabbits grazing beneath the panels.
In 2011, the United Nations Convention to Combat Desertification recognized Kubuqi as a global model for reversing land degradation. Over the past decade, the combined economic output of the region’s restoration and solar projects has exceeded 10 billion dollars, lifting more than 10,000 families out of poverty.
In 1939, the Grand Coulee Dam on the Columbia River blocked salmon migration routes to the river’s upper reaches in British Columbia. No fish ladders were built, and the salmon runs above the dam disappeared. The Colville, Okanagan, Secwepemc, and Ktunaxa nations, whose diets and ceremonies depended on the salmon, experienced a significant loss of a food source that once made up as much as half of what they ate.
In 2019, leaders from these nations launched the Bringing the Salmon Home initiative. The project was guided by an indigenous knowledge council, with elders and knowledge holders shaping decisions. In 2023, approximately 10,000 Sockeye salmon fry, each tagged with a small microchip, were released into the upper Columbia near Castlegar, British Columbia, following a ceremony attended by community members.
In summer 2025, two of these tagged salmon were detected at Wells Dam in Washington, having completed the journey from the ocean back toward the upper Columbia. It was the first documented return of salmon to this stretch of the river in more than 80 years.
The Salmon are returning as governments update the Columbia River Treaty, which governs water management and power generation on the river.
Between 2007 and 2009, the Murray-Darling Basin in Australia experienced a severe drought that stopped river flows and dried up wetlands. Up to 91 percent of freshwater turtles disappeared from parts of southeastern Australia over four decades. The primary cause was predation of nests by introduced foxes, which destroyed up to 95 percent of clutches annually, combined with shrinking habitat.
Starting in 2019, a program led by Associate Professor Ricky Spencer and indigenous rangers collected turtle eggs from vulnerable riverbanks before foxes could find them. Eggs were incubated in temperature-controlled facilities, and hatchlings were raised for 9 to 12 months in protected tanks until they reached a size too large for foxes to consume. In 2021, nearly 10,000 juveniles were released into restored wetlands in the Murray-Darling Basin. The program’s goal was to raise and release one million turtles.
By 2025, more than one million turtles had been released. Satellite imagery showed vegetation recovery along restored waterways, with plant cover in some reaches rising from 3 percent during the drought to over 60 percent. Early tracking indicated that survival rates for released juveniles were significantly higher than in the wild. The program has revived cultural ceremonies among the Yorta Yorta people and other indigenous groups, and international researchers are studying the model.
In 1926, the last wolves in Yellowstone National Park were killed under a federal predator control program. With wolves gone, elk populations rose to nearly 19,000 by the early 1990s. Elk browsed on young trees and shrubs along riverbanks, preventing regeneration. Willow and aspen stands disappeared, riverbanks eroded, and beaver colonies declined to a single surviving colony.
In 1995 and 1996, 31 gray wolves from Canada were released into Yellowstone. The wolves established packs and changed elk behavior, causing elk to avoid open riverbanks where they were vulnerable to ambush. Riparian vegetation recovered, with some valleys seeing significant increases in shrub cover. River channels narrowed and deepened, and beaver colonies expanded to 121 by 2024.
Wolf-related tourism now generates an estimated $82 million annually for communities near the park. The wolf population has remained stable at 100 to 120 animals. Researchers note that drought cycles and other factors also influence the park’s recovery, and wolves acted as a catalyst rather than a complete solution.
Across Africa, an estimated 3.9 million hectares of forest are lost annually. Conventional tree-planting campaigns in dryland regions have had limited success, with more than 80 percent of seedlings dying within a few years. In the early 1980s, Tony Rinaudo, an Australian agronomist working in Niger, discovered that many trees cut down for farmland were regrowing from living root systems underground.
This approach, known as farmer-managed natural regeneration, involves farmers selecting and pruning the strongest shoots from living stumps in their fields. The established root systems provide water and nutrients, allowing the shoots to grow faster than planted seedlings. In Niger, more than 5 million hectares have been regenerated using this method, with more than 200 million trees restored. In Tanzania’s Dodoma region, farmers have revived more than 500,000 hectares using the same approach.
Across Africa, more than 18 million hectares have been restored through farmer-managed natural regeneration at a cost of less than $20 per hectare, compared with hundreds of dollars per hectare for conventional planting programs.
The Great Pacific Garbage Patch, located between California and Hawaii, covers approximately 1.6 million square kilometers and holds an estimated 1.8 trillion pieces of plastic. Roughly half the mass comes from abandoned fishing gear, with the rest from hard plastics and fragments.
In 2012, Boyan Slat, then a 16-year-old from the Netherlands, proposed using floating barriers to collect plastic from the ocean’s surface. He left his aerospace engineering program at Delft University and founded The Ocean Cleanup as a nonprofit, funded by a crowdfunding campaign that raised $2.2 million from 38,000 supporters.
The organization’s first full-scale device, tested in 2018, broke down and failed to retain plastic. Engineers redesigned the system, and System 03, a 2-kilometer floating barrier towed by two vessels, has been in operation since 2022. The system funnels plastic into a retention zone, with a 4-meter skirt that allows fish to pass underneath.
As of late 2025, The Ocean Cleanup has removed more than 45 million kilograms of plastic from oceans and rivers. Twenty interceptor systems operate in nine countries, capturing plastic before it reaches the sea. Recycled ocean plastic has been used in products including sunglasses, car components, and merchandise. The organization’s stated goal is to remove 90 percent of floating ocean plastic by 2040.
